(153f) Development of Sol-Gels and Nanoparticle Enhanced Sol-Gels for pH Sensing Performance | AIChE

(153f) Development of Sol-Gels and Nanoparticle Enhanced Sol-Gels for pH Sensing Performance


Xie, W. - Presenter, University of Minnesota - Duluth
Sol–gel is a wet-chemical process that involves the formation of an inorganic colloidal solution (sol) as the precursor and the gelation of the sol to form a three-dimensional network structure (gel). Sol-gel technology has been applied for the development of optical sensors and biosensors, due to 1) its chemically, photochemically, thermally, and mechanically stable; 2) optically transparent; 3) being formed at low temperature and under mild chemical conditions, allowing the entrapment of molecules with thermal and chemical sensitivity.

The sol–gel process has three major steps: 1) the raw materials (reactants and nanoparticles) were dispersed in the solvent by an ultrasonic treatment, 2) Tetraethyl orthosilicate (TEOS) hydrolyzed to form active monomers, which polymerized to be a sol, and 3) eventually, the sol started to form a gel with a certain spatial structure by aging. Figure 1 shows the intensity spectra for sol-gel pH sensor with cresol red indicator dye.

The incorporation of TiO2 nanoparticles enhances the hardness and elastic modulus of the gel by 0.18 GPa and 3.7 GPa, respectively, so that it provides a good and solid support for the immobilization of the indicator for a better sensitivity and stability in the sensing film. The TiO2-sol-gel film can be used to detect pH in a broad range of 1-12 fast and reversibly. It has advantages over the traditional electrochemical analysis with no charge, strong anti-electromagnetic interference, no pollution, and can be employed to develop optic chemical sensor for remote measurement and multi-channel detection. It can be envisaged that the sol-gels and nanoparticle enhanced sol-gels have great potentials to be the solid base for next-gen sensors.